Antiphospholipid syndrome (APS) is a systemic autoimmune disorder characterized by a combination of arterial or venous thrombosis and recurrent fetal loss, accompanied by elevated titers of antiphospholipid antibodies (aPL). Two forms have bee described: the "primary syndrome" where there is no evidence of an underlying disease, and the "secondary" syndrome, mainly in the setting of systemic lupus eryhematosus. In 1998; an international panel of experts met in Sapporo to establish the classification criteria for definite antiphospholipid syndrome. Two assays are available to demonstrate the presence of antiphospholipid antibodies in plasma of patients: ELISA for the detection of anticardiolipin antibodies and coagulation assays for the detection of the lupus anticoagulants. Treatment decisions fall into four main areas. Prophylaxis, prevention, treatment of acute thrombosis, and management of pregnancy in association with antiphospholipid antibodies.